Jackie, this has been a frequent topic of interest on this list serv. If you perform a search on this site, with"inr" as the keyword, you will see previous posted responses to similar queries.
We do not have any formal guidelines/references to guide us. If we have a thrombocytopenic pt with platelets ~ <20 we usually recommend a platelet transfusion & insert during or immediately post-insertion, unless there is an urgent need for the line. The patient & staff are informed of the risk of bleeding. High INRs also don't preclude a PICC. We would confer with the service to ascertain whether medical intervention (i.e., vit K or fresh frozen plasma) is required prior to the procedure. If the platelets are high, aspirin may be prescribed by the attending. This was supported by an interventional radiologist who presented at an AVA conference in Savannah (unfortunately I don't have the syllabus at hand).
Daphne BroadhurstDesjardins PharmacyOttawa, Canada
Bard Access Systems